Sigma 588954 24-35mm f/2 DG HSM Art Lens for Canon EF + 10PC Accessory Kit EF Mount Lens/Full Frame Format; Aperture Range: f/2 to 16 FLD & Special Low Dispersion Elements; Two Aspherical Elements Super Multi-Layer Coating; Hyper Sonic AF Motor Internal Focus; Manual Focus Override; Rounded 9-Blade Diaphragm Thermally Stable Composite Material; Compatible with Sigma USB Dock